Creep resistant lead alloys

ABSTRACT

A creep resistant lead alloy comprising 0.001 - 1.0 percent by weight of barium and at least one element of the group consisting of silver, aluminum, boron, bismuth, cadmium, hydrogen, magnesium, oxygen, sulphur, antimony, selenium, silicon, tin, tellurium and zinc. The barium and the one or more elements of this group are present in a combination which has been formed either in the liquid or in the solid state of the alloy and which has a dispersion strengthening effect on which leads to order states in the lattice or to order-like states, such as a cluster formation, that produce a strengthening effect.

United States Patent Erdmann-Jesnitzer et al. Oct. 1, 1974 [54] CREEP RESISTANT LEAD ALLOYS 2,013,487 9/1935 Canfield et a1 75 166 R [75] Inventors: Friedrich Erdmann-Jesnitzer, FOREIGN PATENTS OR APPLICATIONS Hammer; Peter Paschal 6051a, 301,380 4/1921 German 75/167 both 9f Germany 307,672 7/1921 German 75/167 1731 Assign Meme, Luxembourg 222113 1311335 821222131113. 3:131:33 111111321123 Grande Duche dc Luxembourg 106,208 4/1927 Austria 75/167 Luxembourg 859,805 12 1952 Germany 75/167 [22] Filed: Nov. 2, 1972 Primary Examiner-L. Dewayne Rutledge [21] Appl' 303203 Assistant Examiner-E. L. Weise Related US. Application Data Attorney, Agent, or FirmJohn J. Dennemeyer [63] Continuation of Ser. No. 13,156, Feb. 20, 1970,

abandoned. [5 7] ABSTRACT A creep resistant lead alloy comprising 0.001 1.0 [30] Foreign Apphcatmn Pnomy Data percent by weight of barium and at least one element July 15, 1969 Luxembourg 59186 of the group consisting of Silver aluminum boron, i

- muth, cadmium, hydrogen, magnesium, oxygen, sul- [52] U.S. CI. 75/167, 75/175 R phur antimony selenium, Silicon tin ll i d 51 Int. 01. C22c 11/00, C22C 13/00 zine The barium and the one or more elements of this [58] Field M Search" 75/167 166 166 I66 group are present in a combination which has been 75/166 166 175 R formed either in the liquid or in the solid state of the alloy and which has a dispersion strengthening effect [56] References Cum on which leads to order states in the lattice or to or- UNITED STATES PAT TS der-like states, such as a cluster formation, that pro- 1,360,272 11 1920 De Campi 75 167 duce a strengthening effect. 1,384,056 7/1921 Fink 75/166 R 2 D 1,804,883 5/1931 Mathesius et a1 75/167 Clams N0 'awmgs CREEP RESISTANT LEAD ALLOYS This is a continuation of application Ser. No. 13,156, filed Feb. 20, 1970 now abandoned.

The present invention relates to lead alloys having improved mechanical properties and is concerned more particularly with lead alloys having high creep resistance.

It is known that lead alloys with a low creep resistance show important drawbacks when used in certain fields of application or their application is considerably limited for this reason. In this connection for example, the low creep resistance of solder alloys is often an important drawback since for example standard solder alloys do not even transmit the stress caused by the thermal expansion of soldered zinc roof gutters having a length of several meters. Furthermore in the electronics and packaging industry solder alloys are limited in their application if they must support a constant load in one direction, and also for example at elevated temperatures.

For lead alloys being used as semi-finished products such as strips, sheets, tubes, wires, the lack of creepresistance is a particularly important drawback.

With respect to the use of lead alloys in batteries, the problems of the creep strength are not as important as the electrochemical problems. The standard alloy for batteries is the PbSb -alloy with varying As contents. The admissible load for this alloy at a limitation of the creep characteristics to 1 percent per year is in the range of 30 to 70 kp/cm at room temperature (Hofman, Lead and Lead-Alloys, Springer Verlag, 2nd edition, page 227). Due to the migration of the antimony and the resulting contamination of the cell, there is still a tendency to reduce the antimony content of such alloys. So far, lead alloys with high creep strength and high fatigue strength without an antimony content are also advantageous for the battery manufacturing industry. Due to the higher rigidity of the alloys of the present invention, the weight of the batteries could be decreased by using grids of less thickness.

Radiation and sound protection are modern fields of application of lead and lead alloys wherein an improved creep strenght is also of importance.

Data on the creep resistance of lead-tin alloys as a function of the tin content are scarcely available from the technical literature. However, values for the creep rupture strength of lead-tin alloys are available. Hofman (Lead and Lead-Alloys, 2nd edition, page 451) indicates as creep rupture strength for a ten day service life with an Sn-content between 32 and 100 percent a tensile stress of 70 Kp/cm Tests made by the inventors have shown a creep resistance of about kp/cm", respectively 12 kp/cm for a PbSn 40 and PbSn alloy with a 1 percent elongation at room temperature.

The object of the present invention is to provide lead alloys having a higher creep resistance by which the above mentioned drawbacks are overcome and new fields of application can be opened.

The lead alloys according to the present invention comprise 0.001 1.0 percent by weight of barium (Ba) and at least one element from the group consisting of silver (Ag), aluminum (Al), boron (B), bismuth (Bi), cadmium (Cd), magnesium (Mg), oxygen (0), hydrogen (H), sulphur (S), antimony (Sb), selenium (Se), silicon (Si), tin (Sn), zinc (Zn), tellurium (Te), the barium and the other element being present in a combination which has been formed either in the liquid or in the solid state of the alloy and which has a dispersion strengthening effect and/or which leads to order states in the lattice and/or to order like states (cluster formation) that have a strengthening effect.

The elements can advantageously be present in the alloy in the following weight percentages:

Silver 0.001 l0 Aluminum 0.001 2 Boron 0.001 l Bismuth 0.001 6 7r Cadmium 0.001 l0 Magnesium 0.001 6 Oxygen 0.001 0.2% Hydrogen 0.001 0.2% Sulphur 0.001 2 7? Antimony 0.001 2 Selenium 0.001 l Silicon 0.001 2 Tin 0.001 Tellurium 0.001 l Zinc 0.001 l Preferred creep resistant lead alloys are those alloys which consist of 0.01 1.0 percent by weight of barium (Ba) and one element in the given amounts of the mentioned group, balance lead or lead-tin.

Creep resistant tests have been made for the alloy according to the invention, Pb-Ba-O comprising for example 0.07 percent by weight of Ba and 0.006 percent by weight of oxygen. From the resulting creep curves (10.000 hours) a value inferior to the admissible 1 percent per year elongation at room temperature could be obtained for a load of 1 l2 kp/cm It results therefrom that the creep resistance was superior to 112 kp/cm high grade lead Pb-Ba-O before rolling 4,15 7,91 after rolling 3,18 10,90

Since a major part of the semi-finished lead products are used in the sulphuric acid industry, the alloys according to the invention must be corrosion resistant to the attack of diluted sulphuric acid. The alloys according to the invention did not show a worse corrosion behaviour than high-grade lead.

Tests on lead-tin-base alloys have shown similar results. On the basis of the creep curves it has been shown that the lead-tin base alloys according to the present invention in comparison to the lead-tin alloys, despite a higher load, had a lower elongation. The charge capacity of the Pb-Sn-base alloys according to the invention at elevated loads is at least twice as high: at low loads there is a discontinuance of the creep action.

Soldering tests with these alloys have shown that the wetting properties of the solder on brass and zinc are at least as good as in the case of common Pb-Snsolders.

What is chimed is' 0.001 1% 0.001 0.2" l. A creep resistant lead alloy cons1st1ng essentlally f- Hydrogen 0.001 0.2% 0.00l1.0 percent by weight barium, Sulphur at least one addmonal element of the group consist- 5 selcmum 1/! ing of silver, boron, hydrogen, oxygen, sulphur, se- Silicon 0- 2% lenium and silicon wherein the barium and at least the balance being lead.

one additional element are in the form of dispersions for strengthening the alloy, the additional elements being present in the following weight m 2. A lead alloy as defined 1n claim 1 wherein t1n 1s tflg present in a percentage range of 0.001 90 percent Silver 0.001 

1. A CREEP RESISTANT LEAD ALLOY CONSISTING ESSENTIALLY OF: 0.001-1.0 PERCENT BY WEIGHT BARIUM, AT LEAST ONE ADDITIONAL ELEMENT OF THE GROUP CONSISTING OF SILVER, BORON, HYDROGEN, OXYGEN, SULPHUR, SELENIUM AND SILICON WHEREIN THE BARIUM AND AT LEAST ONE ADDITIONAL ELEMENT ARE IN THE FORM OF DISPERSIONS FOR STRENGTHENING THE ALLOY, THE ADDITIONAL ELEMENTS BEING PRESENT IN THE FOLLOWING WEIGHT PERCENTAGES:
 2. A lead alloy as defined in claim 1 wherein tin is present in a percentage range of 0.001 - 90 percent. 